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Posted: 10/19/2006 12:44:51 PM EDT
[#1]
Try locking the bolt back. Insert a loaded mag and hit the bolt release. Will it chamber that way?
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Posted: 10/19/2006 12:48:01 PM EDT
[#2]
+1 Let the bolt ride forward on it’s own under full momentum. |
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Posted: 10/19/2006 12:50:02 PM EDT
[#3]
It sounds like you're riding the bolt. Are you sure you're releasing it when the charging handle is all the way back?
When you get this problem is the bullet nose starting to enter the chamber or is the bullet pushing up against the outside of the barrel extension or upper receiver? (pics would help). |
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Posted: 10/19/2006 1:24:54 PM EDT
[#4]
But he said it is happing while firing too, but not as much. These guys are right it could be as simple as you riding it home but that little tid bit makes me wonder.
Just curious what type of ammo you are using? Sounds silly but does it happen with no magazine in the rifle? This would be a hammer engaging the firing pin scenario - not likely though. Factory build or customer build? Pics? |
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Posted: 10/19/2006 1:27:36 PM EDT
[#5]
Which means what? It's only happening when he loads it - or does it occure during the string. He's kinda vauge about the details. |
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Posted: 10/19/2006 1:29:58 PM EDT
[#6]
Good point Forest - I believe teh devul lurks somewhere in the details we need. |
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Posted: 10/19/2006 2:21:33 PM EDT
[#7]
I just gave the whole rifle one hell of a cleaning and tryed again. this time paying close attention to not short strokeing it. I had much better results. out of about 30 manipulations, i still got about 6 falures to feed. the bullet rested up against the lugs of the reciver. the rifle is a 2 1/2 year old bushmaster. and this problem has occured durring strings of fire, but not nearly as often as when i chamber the first round out of a mag.
I am unable to give you guys pics at the moment due to lack of a camera. |
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Posted: 10/19/2006 3:30:21 PM EDT
[#8]
This could be one of many problems! The first question that comes to mind for me anyhow....has your 2.5 yr. old Bushmaster always done this?? And your just now getting around to asking about the problem? Or you may have bought it off someone recently and your pissed now for buying it! heAnother possibility, in which a buddy of mine had this problem with his Bushmaster M-4gery. He called Bushmaster and the Smith there told him the lower portion/edge of the feed ramps probably just need a fine polish, send it in and they would take care of it. Well my bud prides himself on his gun smithing abilities and did it on his own. Long story short....end of problem. I don't know......Just food for thought!!
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Posted: 10/19/2006 5:05:47 PM EDT
[#9]
Thanks for the help but almost none of that aplies to me.  . bought the gun and mags new and dont keep them loaded. the rifle as only been doing this for a 3 or 4 months. I will take alook at the feed ramp though. I never thought of that. thanks again.
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Posted: 10/19/2006 5:15:51 PM EDT
[#10]
Keeping mags loaded does NOT wear them out
 How much lube are you using ? Mike |
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Posted: 10/19/2006 5:31:55 PM EDT
[#11]
Average amount I guess. Its real smooth rite now. And for all future post's, I dont want this thread to turn into an argument about weather or not keeping mags loaded wears them out or not. Thanks. |
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Posted: 10/19/2006 5:42:23 PM EDT
[#12]
What ammo are you using? What ammo were you using before when it was running fine?
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Posted: 10/19/2006 6:10:47 PM EDT
[#13]
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Posted: 10/19/2006 6:28:13 PM EDT
[#14]
Give the misinformation a rest, at the request of the OP. OP, are the rounds handing up on something or is the carrier? |
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Posted: 10/19/2006 6:45:33 PM EDT
[#15]
Ammo what ammo are you using?
You mentioned it didn't matter what mag you used correct? How many mags and what kind are they? Are they all the same? And I apologize but I can't resist - mag springs will not weaken or wear from being compressed. I'm sorry but they won't. |
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Posted: 10/19/2006 6:52:38 PM EDT
[#16]
Just taking a Wild Ass Guess here, but separate your upper and lower. Pull out the bolt/carrier and charging handle. Remove the bolt from the carrier. Check the carrier gas key to see if it’s loose. Now flip the weapons upper receiver upside down. Insert the bolt carrier by it self and allow it to slide forward towards battery. Observe the gas tube as it enters the carrier gas key. Does the carrier slide freely back and forth without dragging on the gas tube?
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Posted: 10/19/2006 7:22:45 PM EDT
[#17]
For real. The "mag springs wear out/get weak when stored loaded" horse has been beaten way past death, and it's still not true. Ask Larry of CProducts. It's not compression that makes springs weak - it's compressing and uncompressing (cycling). You can push a mag spring all the way down and leave it for years with no bad effects. Chrome silicon springs can take more of those cycles before wearing out, but stainless steel is not bad either. If you suspect the buffer spring, why not just get another one? What kind of stock do you have - fixed or carbine/collapsible? |
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Posted: 10/19/2006 7:41:11 PM EDT
[#18]
The D&H and Bushmaster mags (D&H) are known to do this when new - due to sharp feelips. Mine will not always strip the round from the bolt release. They work pretty well under fire, and then work perfectly once broken in.
Sounds like yours may be a combination of these mags, and a weak buffer spring. I would replace the buffer spring,a nd repeat your tests with the 20 round mag. It should not malfunction with that mag.... or malf once your feedlips smooth out. |
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Posted: 10/19/2006 7:42:54 PM EDT
[#19]
Eureka!! I concur. You may actually have a screw loose heDamn Good QUIB!! |
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Posted: 10/19/2006 7:47:08 PM EDT
[#20]
If you suspect the buffer spring is out of spec try measuring it.
Rifle buffer springs should have a free length of 11-¾” min to 13-½” max. Carbine buffer springs should have a free length of 10-1/16” min to 11-¼” max. |
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Posted: 10/19/2006 7:51:20 PM EDT
[#21]
I was having a similar problem with my Bushmaster as well (failure to feed). My rifle came with 4 mags, three 30 round and one 20 round. I replaced the springs and followers, but the problem still persisted. As a last resort, I purchased a couple of new mags (from DPMS) when I was at our last gun show and I haven't had a problem since. I only fired about 80 rounds through the new mags, but it was a good sign that no rounds were misfeeding. I hope you solve your problem soon.
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Posted: 10/19/2006 9:03:30 PM EDT
[#22]
Right but instead of going through all of this just see if it happens with the magazine out of the rifle. Right? If it works fine with no magazine present then we rule out the loose screw theory and narrow it down to the mags. Si or No? |
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Posted: 10/20/2006 5:05:08 AM EDT
[#23]
Si or No? Maybe. It won’t rule out the fact that he could have a slightly loose carrier key allowing gas to escape causing short stroking. That can only be determined by physically inspecting the carrier. Of course you could perform the test with the rifle assembled and a very seriously dragging gas tube might be evident. But I think it would be advisable to do the test with a stripped carrier as I mentioned above. It’s really the only way to see if the gas key and gas tube are binding even the slightest. I also perform this "drag check" when ever I’m assembling an upper. |
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Posted: 10/24/2006 2:16:51 PM EDT
[#24]
You will have to forgive my ignorance but wich part exactly is the gas carrier key. I belive it is the part that catches the hot gas out of the gas tube and is bolted to the top of the carrier, but im not 100% sure on that. either way, no, the carrier dose not slide very smoothly around the gas tube. P.S. Sorry it has taken me so long to reply, i have not had much free time or much access to a computer the last few days. |
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Posted: 10/24/2006 2:34:19 PM EDT
[#25]
You are correct on what the carrier key is. I am having a similar problem on my new CMMG upper. But it is getting better as I fire more rounds through it. |
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Posted: 10/24/2006 3:07:41 PM EDT
[#26]
Your correct in identifying the gas key. Slide the carrier only into the upper receiver and observe where the carrier key and gas tube make contact. The manual states to gently bend the gas tube underneath the hand guards, then drop the carrier back in, and repeat as necessary. I use a large flat tip screwdriver and gently bend the gas tube inside the upper receiver, in the opposite direction from where it’s dragging. The method and how/where you bend the gas tube is up to you, but that is where I personally would start addressing this problem. |
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Posted: 10/24/2006 4:48:16 PM EDT
[#27]
Upon further inspection of the gas tube I noticed it dose seem to be bent a hair to the left. I have a GG&G non free-float modular handgaurd so perhaps i can stick a screwdriver in one of the top holes and use the gaurd as leverage to move the gas tube into the correct position/shape. Hopefully this will fix the problem. Thanks. |
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Posted: 10/24/2006 5:22:44 PM EDT
[#28]
You may be able to bend it but most likely the barrel nut needs aligned with the cruciform hole in the receiver. That is probably what is misaligning the gas tube.
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Posted: 10/24/2006 9:10:10 PM EDT
[#29]
One of the most overlooked problems is a mag catch slot milled too low on the lower receiver. This causes the magazine to sit too low in the rifle and makes the rounds hit below the feedramps.
Can you take a caliper and measure the distance from the top of the lower to the top of the magazine catch slot? This distance should be 0.650" |
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Posted: 10/25/2006 6:38:07 AM EDT
[#30]
This part made me curious. Buddy of mine had similar results on his brand new Modular Carbine few months back. Bullet stuck always on left feed ramp. This made me think it is gas leak, like bolt carrier wouldn´t have enough thrust to push fresh cartridge from magazine. We went through whole rifle, magazines (a lots of) gas key screws, gas tube to gas block fit, ammunition, buffer spring, buffer, another lower but no help. Problem occured every once in awhile, no matter what we did. Gas tube to gas block fit was very loose, btw, but that wasn´t problem. I was about to give up but then we noticed tiny copper particles inside barrel extension. We didn´t notice this earlier since we focused on possible gas leak. We went through cartridges left over from stoppages and found out marks on those bullets stopped to left side feedramp were different than normally, grooves were significantly deeper and differently shaped. At this point owner said I´m free to do anything with rifle, it doesn´t work anyway. He was pretty upset since he paid shit load of money to get it. He even suggested me to Dremel some material off the lugs but I said I wouldn´t remove material from barrel extension but I can do some slight polishing. Polishing was done with 1000 grit paper wrapped around needlefile with very skeptical feeling but what the hell it could be worth it. Lo and behold, it worked! Not a single feeding or any other problem in that afternoon. Problem solved.  Last time I asked owner round count after polishing and he told at least 1500 shots w/o single malfunction... Just my .02 cents. MN |
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Posted: 10/25/2006 7:37:11 AM EDT
[#31]
I was having this problem a few weeks ago too. Is your buffer spring greased? Many people do this to get rid of the noise it makes when firing. Mine was. As the grease got old and dirty is started clumping up and it was slowing down the bolt carrier return a bit. Cleaned out the tube and cleaned off the spring. No problems since. Bolt closes with authority now. No more lubed buffer springs for me.
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Posted: 10/26/2006 2:59:33 PM EDT
[#33]
If I measuered what you said to measure, It would seem that the space is actually 0.680" How bad is that? (this is the first time i have ever measuered anything with calpers). |
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Posted: 10/26/2006 3:35:10 PM EDT
[#34]
Can you re-size and re-post those pics? You’re over loading my dial-up connection!
It could be that your gas tube is cocked to one side because of your barrel nut not being aligned, as already stated above. Have you tried to straighten out the gas tube? ETA: Never mind the pics finally loaded up. And yes, it looks like your gas tube is cocked to one side. |
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Posted: 10/26/2006 3:42:08 PM EDT
[#35]
Sorry for th size of the pics. it was my first time. So if it is the barrel nut, what do i do? something the local smith can fix? I tried to move the tube with a screw driver but didnt get anywear. wasnt sure about tryin to bend it though, didnt wnat to do more harm then good. |
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Posted: 10/26/2006 4:12:10 PM EDT
[#36]
If you don’t own the necessary tools or know someone who does own the necessary tools, then I would seek out a smith who can help you out. (Ask in your home town forum. Maybe someone with the tools can help you out.) If your barrel nut is in fact not aligned with the receiver and pushing your gas tube to one side then your free-float tube would need to be removed, the barrel nut re-torqued and aligned and I would recommend a new gas tube. |
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Posted: 10/26/2006 4:47:05 PM EDT
[#37]
I think my local smith can handle all of that, but wear can i get a gas tube? and what do u think about the mag catch being machined to low. that dose sounds like it could be caauseing the problems i have been haveing?
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Posted: 10/26/2006 5:36:38 PM EDT
[#38]
A gas tube can be had from any of the parts dealers in the Industry Section of the site. As far as the dimensional check that Scott Ryan gave you, I have no idea, you’ll have to ask him for more direction. |
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Posted: 10/26/2006 5:41:44 PM EDT
[#39]
I had the same problem, except i never looked at the gas or key ( properly staked and using two piece handguards not free float) be cause barrel nut linned up. Take off the handguard and see if the barrell nut lines up with the hole in the upper reciever, if not correct the problem as the friction may be slowing it down just enough.
However the fact that you said it happens only on the left side makes me think that the feed ramps are suspect. After manually (pulling back charging handle releasing, and pulling back again to extract round) extracting round are there scratch or gouge marks on the bullet. If so it is more than likely the feed ramps. I had the same problem as i said, use different kinds of mags and ammo, different buffers and springs, still had problem. The only area that had not been looked at was the Barrel and barrel extension where the ramps are located. what i did to remedy my problem was check barrel torque retorque to spec, and also polish feed ramps. POLLISH FEED RAMPS there is also another threadover on the troubleshooting area thathas this same problem. |
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Posted: 10/26/2006 6:14:52 PM EDT
[#40]
 Seriously.....you are a [Inappropriate comment for the Tech areas - Forest]! An indefinately loaded mag spring will not be worn out. Static tention does NOTHING to a mag spring.......always keep a few mags loaded all the time, and in 30 years they'll still be fine. |
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Posted: 10/26/2006 6:43:36 PM EDT
[#41]
Excuse me.......No need for personal attacks, [Inappropriate comment for the Tech areas - Forest]! ! I was just trying to relay something that may be a Mag Spring issue..... i.e. "Weak Spring!" Obviously that is not the case. |
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Posted: 10/26/2006 6:43:37 PM EDT
[#42]
quib - back to our discussion about testing to rule out the gas tube. If the mag is removed and he doesn't have any failures going in to battery can it still be the gas tube? Could the "rub" of the tube inside the key and the added force needed to strip a round cause this failure to feed? I'm interested to hear more about the measurement ScottRyan had him take. Amazing what you can learn around here by staying away from GD. 
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Posted: 10/26/2006 7:24:10 PM EDT
[#43]
Quib,
Look at the photo of the gas tube under the handguards. Is it me or does it look like the gas block is off alignment a bit? Looks like the tube enters the receiver at an angle, but one that is started at the gas block not the barrel nut. What do you think? |
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Posted: 10/26/2006 7:32:42 PM EDT
[#44]
That seems normal but on the high side. But from the pics, you definately have an alingment problem with your gas tube. I would try to get that corrected first. Make sure your calipers are square to the part when you measure. |
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Posted: 10/26/2006 8:20:53 PM EDT
[#45]
Where's the flare at the end of the gas tube? All my ARs have a flare that looks like a fatter rim near the very end of the gas tube for the bolt carrier's gas key to lock up on. It sort of makes the end of the gas tube look like a mushroom with the very top cut off from the side.
Your tube looks like a rifle or mid-length tube that's been cut down, or something (or really worn on the end). I'd definitely replace it first like the guys above say. You can get them from everywhere from MidwayUSA to Bravo Company for about $12.
Looks to me like your handguards are a few degrees too far clockwise, looking down the barrel with the AR shouldered. They don't line up with the flat side straight on the upper and the FSB. |
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Posted: 10/26/2006 9:55:45 PM EDT
[#46]
First off, I wouls like to thank everyone for there contribution to my problem. I have learned a great deal so far. I do feel that most of my problem lies with the gas tube and the barrle nuts alingment to the reciver. Im going to take it to the smith tommarow and see what he says. Also, could someone post a pic of a gas tube like what engineer2001 was talking about? I have never seen one like what he discribed. (not that i have seen many anyways) 2nd- I hate to ask another stupid questin, but could someone show me a pic detailing the feed ramps. So I can make sure I understand the advice im getting. It seems I need to spend more time on my AR-15 termanology  3rdly (spoken in a friendly but stern tone)- I would like to AGAIN ask that the subject of "loaded mags wear out springs" be forever dropedin this thread! This topic has been beaten beyond recognition on this site and it dose not matter anyway because none of my mags have been kept loaded. There is also no reason for personal attacks! No one is telling anyone what they can or cant do with there mags. If you feel someone is doing something wrong, fine. Tell them what you think, hope they listen, but if not, O'well, its not your problem! |
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Posted: 10/26/2006 10:30:43 PM EDT
[#47]
The feed ramps are the things that are cut into the bottom of the barrel extension that the bullet tips hit and ride along when the round is being chambered. See the two channels cut out in each of the barrels below (regular rifle ramps and bigger M4 ramps)?
 The end of the gas tube that has the flare that I mentioned is hard to photo... checking now to see if anyne has a pic online I can borrow. ETA: AHA! You can see it in this pic:  That's a rifle-length tube, but all my gas tubes (rifle and two carbines) are like that - fat flare/ring at the end that fits inside the receiver (the left end in the above pic). |
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Posted: 10/27/2006 2:31:10 AM EDT
[#48]
I agree Forest. And I’m not saying the gas tube alignment is his ONLY problem. It may be one of a few problems. But as I stated above, if this was my rifle, given the photographic evidence he has shown us, that is where I personally would start troubleshooting. |
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Posted: 11/1/2006 11:05:02 AM EDT
[#49]
OK. so Ive just got the chance to drive over to my local smith and he fixed the gas tube alignment problem. Hopefull I will get a chance to acctually fire the gun in the next couple of days, but for now Im just gonna go hand cycle a couple of mags and see how it works. ill post again after im able to fire it.
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Posted: 11/1/2006 11:27:27 AM EDT
[#50]
I had almost the exact same problem with a gun a bought from a fellow years ago. It would rarely feed more than one or two bullets at a time before it would stop cycling completely. I too was told it had to be a gas tube issue, which under most circumstances would probably be right, but in my case I simply tried new ammo. I realized that the bulk ammo I had been using wasn't strong enough to cycle the gun. By upgrading to XM193 my problem immediately went away and the gun has worked perfectly ever since.
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